If you have a popup blocker, make sure it is not blocking the window from displaying.
You can alternatively open the broadcaster in a new window by going directly to this link
http://www.earthcam.com/myec/yourwebcam/webcam_popup.php

3) When the broadcaster loads you will see a message that asks you if Flash can access your camera and microphone. Click "Allow". (Clicking 'deny' will prevent the broadcaster from accessing your camera.)

4) You can tweak the settings, standard or widescreen sizes, and the picture quality here as well. Once you're happy, click "start broadcast", and the button will turn red.. Open up your MyCam Page and you should see your webcam feed. (If you have it open already you may need to refresh the page in order to see the feed).

note: please make sure "Display Webcam" is set to "Yes" on your account management settings.
http://www.earthcam.com/myec/account_edit.php